540 RAT responds to Questions/Comments from Readers of this Blog.
Hi Rat, thank you for the facts, been trying to educate myself on oil performance and this Is the only data I can find on oil film strength. Posted this on a Dodge Ram forum and got blister and ridiculed, mainly because it proved them all wrong. 30w oil is better than 20w oil and all you need it moly in your oil and your bullet proof is all you hear, and is highly incorrect.
Anyway, I have a Hemi 5.7 I use for street / strip and was interested in switching from 5w20 to 0w20. I know the Quaker State 0w20 (new green bottle) had very good film strength performance. Just want to get your input on the switch, and would like to send in a sample of Amsoil 0w20 for you to test.
Thanks in advance, and thank you for your continued efforts.
Yes, it is very common for car guys on Forums to have no idea what they are talking about when it comes to motor oil. They just repeat the same old MYTHS with absolutely no data to backup anything they say. So, never believe anything people say about motor oil on Forums.
To answer your question, let’s take a look at what is specifically going on with motor oil at cold start-up vs what is going on with it at hot operating temperature. For this comparison purpose, multi-grade motor oil viscosity properties are typically given at 40*C (104*F) and at 100*C (212*F). And its thickness is given in an accurate measurement called centistokes (cSt). The HIGHER the cSt value, the THICKER the oil.
Typical Examples of Actual Motor Oil thickness (But, any individual oil’s specific thickness may vary somewhat)
cSt @ cold 40*C (104*F) / cSt @ hot 100*C (212*F)
0W20 = 44.9 / 8.5, or 5.3 times thicker when cold
0W30 = 53.8 / 9.6, or 5.6 times thicker when cold
0W40 = 79.9 / 14.3, or 5.6 times thicker when cold
5W20 = 51.6 / 9.0, or 5.7 times thicker when cold
5W30 = 62.4 / 10.8, or 5.8 times thicker when cold
5W40 = 87.2 / 14.7, or 5.9 times thicker when cold
10W30 = 71.8 / 11.5, or 6.2 times thicker when cold
10W40 = 96.5 / 14.7, or 6.6 times thicker when cold
10W60 = 168.5 / 24.1, or 7.0 times thicker when cold
15W40 = 105.0 / 14.8, or 7.1 times thicker when cold
15W50 = 133.8 / 20.2, or 6.6 times thicker when cold
20W50 = 170.0 / 20.2, or 8.4 times thicker when cold
Looking at 0W20 and 5W20, notice how the thickness of the cold viscosity rating (the number BEFORE the W), also affects the thickness of the hot viscosity rating (the number AFTER the W). The hot thickness of 0W20 is 8.5 cSt, while the hot thickness of 5W20 is 9.0 cSt. So, hot 0W20 is about 5.5% thinner than hot 5W20, which would result in somewhat of an oil pressure drop.
Therefore, with 5W20 already being very thin to begin with, I would not recommend going to the even thinner 0W20 for use in a Street/Strip car. That might just be pushing your luck a little too much. I’d recommend staying with 5W20 in your case. But, Grandma’s grocery getter would be a different story.
As for sending me oil to test, I should be able to begin accepting additional oil for testing in about a month. So, check back with me right after Labor Day. If you are still interested in sending me oil then, I can provide shipping instructions at that time.
I have had a number of people make the same request about sending me oil for testing, over the past few weeks or so. I told all of them the same thing, to check back with me right after Labor Day. Typically about 90% of the people who ask about sending me oil, never follow through. So, it will be interesting to see how many people follow through this time.
Love the blog. Very informative. This might quality for real world testing. 11 years ago I built a sbc for my suburban. Flat tappet cam. Hydraulic. I used castrol 10w-40 for break in. And used it every 3000 to 5000 miles for 11 years. I pulled boats, car trailers, bobcats, mini excavator etc. Never had any cam or lifter problems in those 11 years. Didn’t use any additives or anything. Just conventional castrol oil. Other than compression, and valve springs motor was stock. My recent motor build, jeep 4.0, 1 year so far, only used 5w-30 Quaker state ultimate durability. Runs great and very quiet. I’ll run this oil for as long as I have the Jeep.
Yes, you did do real world testing. Thanks for sharing your experience. And your results prove once again that high zinc oils are not needed for flat tappet cams. All you need is an oil that produces excellent psi values in my Engineering tests, no matter how much zinc it has in it. And that is just as I have been saying all along.
But, a WORD OF CAUTION:
5W30 Castrol GTX, API SN conventional, a few years back, produced 95,392 psi in my Engineering testing.
Now, the latest 5W30 Castrol GTX “ULTRACLEAN, API SN conventional, produced only 78,664 psi, when I recently tested it. This oil’s wear protection capability dropped 16,728 psi, and it dropped over 50 Ranking positions, compared to the previous 5W30 Castrol GTX that was NOT called ULTRACLEAN.
I have had a report from one Blog reader who used the older 5W30 Castrol GTX version for years in flat tappet engines without issue. But, he has now wiped flat tappet lobes during break-in with this latest 5W30 Castrol GTX “ULTRACLEAN” version.
Castrol’s gold bottle Edge motor oils have also significantly dropped in capability, in my testing between its older and newer versions.
In general, I recommend for any engines that may be critical for which oil is used, that you only look at the data from fairly RECENT tests I have performed. That way you can be more confident that my latest posted data will be for the same exact oil that you can actually buy “now”. Oil Companies change their oil formulations over time, and not always for the better.
My recommendations for traditional American flat tappet pushrod V-8 engines specifically:
Stock or lightly modified versions of those engines are best protected by oils that provide 90,000 psi or higher film strength/load carrying capability/shear resistance.
Racing and High Performance street versions of those engines are best protected by oils that provide 100,000 psi or higher film strength/load carrying capability/shear resistance.
540 Rat, I was wondering if you had tested the Valvoline 5w30 Fully Syn with Max life High Mileage (Silver Bottle) rated 123,470 PSI at normal temps – But did you test it at 275 F and if so what was the breakdown % at that temperature. Thanks.
All the data I have on that oil, is already posted on the Wear Protection Ranking List. There would be no reason for me to hold data back.
I can’t seem to find it and I’ve read through more than several times – in a brief what percentage did it go down at 275 F? Thanks again.
There is no extra high temp data for that oil. Like I just told you before, all the data I have on that oil is already posted on the Wear Protection Ranking List. As you should be well aware, only select oils get additional testing. And that oil was not one of those oils.
Great wealth of information, thanks for posting so all can peruse!
If my concern seems valid, please advise- Recently got a 2016 Mazda CX-9 and the salesman / dealership noted it has synthetic oil in it. 2.5 skyactiv turbo, 250hp/310 trq.
We got a mgr demo likely with just under 5000 miles at time of our purchase. Has full as new warranty and I got extended as well- even the dealership LOF/synthetic is pre paid/included.
Since then, I noted lots of confusion on many car forums as the O Man states 5w-30 and not specifying conv or syn. In your opinion is sny or syn blend better than conventional motor oil. I ask because I’m torn between the obvious lack of spec for synthetic these days (seems suspicious or for good reason?) and the flip side of that is my thinking the heat related stress from most turbo motors would indeed benefit from synthetic.
Any thoughts ?
I’m glad to hear that you like my Blog.
The best choice for turbo engines is a quality, full synthetic motor oil, that has performed well in my testing, which then puts it highly ranked on my Wear Protection Ranking List.
540 Rat – Have you heard anything about Pennzoil Ultra Plat 5w30 burning off quicker than Say Valvoline Full Syn Max Life or Mobile 1 5w30. In my 2001 Silverado 2500 with 8.1 Gasoline Engine I needed to add 1 qt after 1,000 miles which I did not have to do before. Thanks.
Any 5W30 full synthetic mainstream motor oil has the potential for high consumption in an old worn, quite high mileage vehicle like your truck (if I’m correctly remembering what you have said about your truck in the past. It can be hard to keep everyone straight, from having questions from so many different Blog readers). So, that type of oil may not be the best choice for the specific condition of any one particular engine, when it comes to oil consumption.
A better 5W30 choice for a vehicle like that, that has a problem of using a lot of oil, is to select a High Mileage oil such as 5W30 Valvoline Full Synthetic High Mileage with MaxLife Technology (silver bottle).
And an even better 5W30 choice is a synthetic blend High Mileage oil, such as 5W30 Valvoline MaxLife High Mileage, synthetic blend (red bottle), because it has more conventional oil, and less synthetic oil in it.
And the best 5W30 choice for your application, to minimize oil consumption, would be a conventional High Mileage oil, such as 5W30 Pennzoil High Mileage Vehicle, API SN, conventional.
If you are still not satisfied with the oil consumption from all those oils, then you will need to go to thicker 10W40 High Mileage oils, such as 10W40 Valvoline MaxLife High Mileage, synthetic blend (red bottle), or 10W40 Pennzoil High Mileage Vehicle, conventional.
All these oils produced over 90,000 psi in my testing and would be excellent oils to protect your truck’s engine. Remember, most engines do not have to always use only the absolute top ranked oil. There are many oils available that provide excellent protection for normally driven vehicles.
Perfect, Thank you !
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